


9th Prince of Gehenna

by ImPanDuh



Category: Ao no Exorcist | Blue Exorcist
Genre: Demon Okumura Rin, F/M, Gen, I don’t know what to tag, I only watched the anime so don’t expect any accuracy on Gehenna, Okumura Rin was Raised in Gehenna, Platonic Relationships, can be seen as either - Freeform
Language: English
Status: Completed
Published: 2020-03-10
Updated: 2020-12-02
Packaged: 2021-02-28 20:02:47
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 1,851
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23093038
Author URL: https://archiveofourown.org/users/ImPanDuh/pseuds/ImPanDuh
Summary: “I’m Rin, 9th Prince of Gehenna. And heir to the throne”Shiemi doesn’t know how she managed to rip the paper.
Relationships: Moriyama Shiemi & Okumura Rin, Moriyama Shiemi/Okumura Rin, Okumura Rin & Mephisto Pheles
Comments: 13
Kudos: 353





	1. Chapter 1

Shiemi looked at Izumo in awe. She was a tamer! A rare skill! Shiemi hoped she would also be one so she could get along better with Izumo! She pricked her finger with the needle, flinching at first, but she was determined and pierced until she saw blood coming out. She smeared it on the paper, wincing a little at the sting. She tried to think of a cool phrase (maybe a poem?) to say, but came up empty. A little embarrassed she whispered. 

“Come out, come out~”

She wanted to add a ‘just kidding’ when the small boy next to her (Koneko his friends called him?) looked at her weird. But Shiemis paper started glowing and a person appeared. Shiemi dropped the paper in shock and took a couple steps back. The rest of the room was equally surprised. Neuhaus’ and Izumos demons reacted weirdly upon seeing the boy (demon?) Shiemi had summoned. 

The first thing Shiemi noticed was the boys white to light blue hair, next his leather jacket. The first thing she knew she should have noticed were the blue flames that accompanied the boys arrival. Everyone was visibly scared and to their own right! Shiemi might have just summoned Satan himself! But somehow... Shiemi felt oddly calm about this. As calm and content as when she was in her beloved garden. 

“Moriyama-san! The circle! You have to rip it!”, Neuhaus’ scream alerted her back into paying attention. The boy (Satan?) hadn’t done anything since his arrival, except yawn and stretch. He looked around confused, until Neuhaus alerted him to the paper Shiemi had dropped. Shiemi reached for it, but his hands were faster. 

“Huuuh, so I was summoned here?”, he drawled, inspecting the small paper with the simplistic rune. He frowned a little and Shiemi felt that this summoning circle was unfit for someone like him. _She’d have to make something more fitting for him._ When the rotten demon attacked the boy on Neuhauses command, he simply sidestepped and held its head down, not looking away from the paper. The demon whined and whimpered, seemingly conflicted on who it should listen to. 

The boys eyes met Shiemis gaze and she was sure she had never seen such a nice blue before in her life. Even Yukios couldn’t compare. She felt her breath being caught in her throat. She was sure she wouldn’t be able to move, even if she wanted to. The boys eyes held such authority, but also a playful twinkle. The gap was confusing, but fit him so well. 

“Are you satan?”, Suguros loud voice boomed through the classroom. He stood farther back than before and had Shima and Konekomaru hidden behind him. He looked scared but determined. Rin frowned, sticking his tongue out in a disgusted way. His sharp teeth were visible and Shiemi swallowed. 

“Oh hell no”, he answered and Shiemis knees buckled at the sound of his voice. She actually fell to ground, overwhelmed. The boy caught her and placed her down softly on the ground. He sat in front of her, cross legged. _Cute._ “Are you the one who summoned me?”, his question was directed at Shiemi. Neuhaus’ rotten demon attempted to attack the boy again, but was held down easily again. 

“Moriyama-san! The circle!”, Neuhaus urged. Shiemi snapped out of her stupor and hesitantly reached a shaky hand out, palm up. Obediently the boy put the small paper in her palm. A shock traveled around the room at that. 

“Who- who are you?”, Shiemi asked, clutching the paper close to her chest. She handled it with care, feeling like it was something extremely precious. The boy grinned in response, showing off sharp fangs. 

“I’m Rin, 9th Prince of Gehenna. And heir to the throne”

Shiemi doesn’t know how she managed to rip the paper. 

Shiemi didn’t know what else to do. Neuhaus had forbidden her from ever trying that again, but... it was already exhausting for her to stay awake, so Ni-chan would stay and keep up his barrier. The others were also giving it their all, Izumos foxes had slipped past the branches to battle the rotten demons. Shima was keeping them from breaking the branches with his staff and Suguro and Konekomaru were chanting mantras. Paku was helping her stay awake. She would have to...

With shaky hands, Shiemi pulled the paper out of her pocket. She had worked on making a summoning circle that would fit _him_ better. Even if she hadn’t thought that she’d summon _him_ ever again. She used the blood from the wound of summoning Ni-chan to activate it. 

“Rin, come... out, please help us...”

Shiemis eyes closed as she felt it work. It went quiet for a moment. Suguro and Konekomaru had stopped chanting in surprise and even the rotten demons stopped their attack. Shiemi smiled as a rough hand rested on her cheek, his thumb rubbing under her eyes. 

“Come on, stay awake Master”, he grumbled and Shiemi opened her heavy eyes to look at his disgruntled face. Rin hadn’t changed since the last time she summoned him that time in class. He still looked as regal as before. 

“Rin”, he hummed in acknowledgement, bowing his head, “Can you help us out?” Rins grin at that looked almost feral, but the cheery twinkle in his eyes kept Shiemi from being scared. She couldn’t be scared of Rin, or he might turn against them. 

“Of course, Master”, he answered, getting up and turning to the rotten demons behind the barrier. Hesitantly, Suguro and Konekomaru took up chanting again. The rotten demons got out of their stupor and fought back with their all. Shiemi had to be careful to stay awake. Rin snuck through the barrier and covered his nose. “Astaroths demons are so disgusting”, he grumbled. 

Everyone could see the blue flames through branches. Konekomaru flinched and stopped his chanting again for a minute, only starting again because Suguro nudged his shoulder. Shiemi felt bad for making them see this, but she didn’t know if they could have held out longer. 

Rin on the other side of the barrier was positively _pissed._ He hated Astaroth and he hated his demons. They stunk and they all treated him as some high and mighty being. Even these summoned ones were holding back as to not hurt him too much. The wounds they inflicted on him would heal slightly slower and stung, but it was better than having someone tiptoe around you. The fox demons were at least slightly more bearable. They were busy with battle and didn’t have the time to treat him like a prince. 

The rotten demons were surprisingly resistant to his flames, but the first one eventually fell, not even a minute after, the second one was exorcised via the mantras. The barrier fell and Rin feared that Shiemi had passed out. But he and the small larvae stayed in Assiah. Rin made his way back to Shiemis side, but caught side of a pink haired boy. The boy flinched when he met Rins gaze, but somehow his fear felt fake. Rin stepped closer, trying to think. Something about him seemed familiar. Or off. He was weird. Something was different. Rin ignored the shouts of the other two boys in the room and stopped in front of the pink haired one. His eyes flickered nervously back and forth, his grip tightening on the staff. 

“Hey, you-“, Rins words were cut off with the sound of a gun shooting. He grunted and clutched at his bleeding side. Rins gaze flickered to the source, a woman who had hidden in the upper bunk. An angry growl filled the room, then he felt another shot in his leg. Shiemi screamed and scrambled to try and get up. Rin was at her side in an instant. 

“Don’t worry Master, I’m fine, this is nothing”, he coaxed her into sitting back down, “you’re safe now, so hurry and rip the circle”. Shiemi defiantly shook her head no and Rin grinned. He had never met someone like her. “It’s fine, come on, you need some rest”, he tried to persuade her and made space for a doctor to tend to her. Shiemi pouted and tried to shake her head no again, but passed out during the motion. 

Rin went back to Gehenna with a grin on his face, even with the rotten wounds and gunshots. When Amaimon made fun of him, he just punched him in the face, although that barely helped with shutting him up. It did help, when Astaroth tried to lecture him about not letting himself get summoned like some kind of lesser demon.


	2. Chapter 2

**Summary for the Chapter:**

> “Don’t worry, Rin. Big brother will protect you”

“Did he hurt you again?”

Rin stopped rubbing his teary eyes to look up at his older brother. He sniffled, curling up further and nodded. He heard Mephisto sigh before his footsteps came closer. Rin felt him sitting down next to him and then how Mephistos arms wrapped around him. 

“What was it about this time?”, he asked, pulling the sniffling child into his lap. He started stroking his hair and rubbing his back, rocking lightly. Rin couldn’t answer, too choked up. Burn marks, deep scratches and other wounds still healing. He buried his face in Mephistos chest, tiny fingers curling into the white fabric. Mephisto waited, humming a lullaby he heard Shiro sing to Yukio. 

The world truly was cruel.   
Even though Yukio could see demons since birth he was able to live in Assiah as a relatively normal child under Shiros care.   
Rin had been found by Satan before Mephisto or Shiro could get to the twins. He must think Yukio didn’t inherit anything and left him there. But Rin had been brought to Gehenna and raised as a demon king. He’s always been a rebellious kid and it was likely Mephistos fault for encouraging his behavior. To stand up and say no when he didn’t want to do something. But he was punished so severely every time. Mephisto was careful while rubbing his younger brothers back to not touch any of the wounds. His healing ability would improve over time, but right now it would take another hour to heal wounds inflicted by the blue flames. He’s been healing for a while already by the looks of it. 

Mephisto stayed like that patiently, patting and rocking the little Rin in his arms, while humming tunes of all the songs he heard over the hundreds of years he’s been alive. Eventually Rins sobs subsided until he was just slightly shaking. He still didn’t move away from Mephisto, but at least his grip relaxed and his claws retracted from where they were piercing into Mephistos skin. 

Even though he never cared much for other beings - the whole world his playground more than anything else - Mephistos eyes went dark at the thought of how much more pain Rin would have to endure if he stayed here. So he made readjustments in his plan. 

“Don’t worry, Rin. Big brother will protect you”

Rin would come to Assiah with him, whether Satan liked it or not - not like he could follow them there.

**Notes for the Chapter:**

> No, I’m not continuing this, I just had this sitting in my notes and had the motivation to upload it. Thank you all for the support though!
> 
> This would be in a slightly different au than the first chapter, where Mephisto sneaks young Rin into the human world where Satan can’t follow - which would probably cause a second Blue Night - and Rin grows up as an exorcist in the human world and later meets Yukio and the others. Yukio would probably enroll into the exorcist school later than in canon since he wouldn’t be exposed to demons without Rin by his side? There’d be lots of comedic and angsty scenes about their possible relation, since they wouldn’t know there related and I’m rambling. Bye bye

**Author's Note:**

> Might add more if I ever get random bursts of inspiration again.


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